The present invention concerns an apparatus for clamping, holding and presenting weft threads in gripper weaving looms.
More particularly, the invention concerns an apparatus designed for weaving several weft threads without waste on the weft insertion side.
It is known that by weaving several weft threads in gripper weaving looms, the different threads are respectively held after their last insertion by means of separate waste threads located near the usual chain threads. Each weft thread is held this way by the waste threads to a moment just before the insertion of the following weft thread whereby the weft threads are kept essentially perpendicular to the edge of the woven cloth. The waste threads, as well as the ends of the weft threads held this way are cut off at some distance behind the fell, as waste of the woven cloth. Quite obviously a relatively large quantity of weft threads, as well as waste threads, are lost this way as waste.
A known solution for this problem comprises the method described in the patent DOS No. 25 15 609, whereby the weft threads are immediately cut off after the insertion in the shed and are stored in an adequate manner by means of a pneumatic device until the insertion of the following weft thread, whereby no waste threads are required. This method, as well as the device used to this end, has the disadvantage that a pneumatic device or a connection to a compressed air source is required.
Another solution for weaving without waste is described in U.S. Pat. No. 4,143,684 whereby the weft threads are kept taut at the presentation to the gripper between thread eyelets and a common device for holding the thread ends, whereby the latter consists of a suction device. This way, only one thread is kept in the suction device and is presented to the gripper while the other thread is still connected with the edge of the cloth. This device has the disadvantage that it is only suitable for working with a maximum of two weft threads.
Another disadvantage is that these two weft threads must be alternatively presented, without the possibility of introducing the same weft thread two or more times successively into the shed.